test otel

pkg/inventory/redis_service.go

@@ -88,19 +88,49 @@ var (
 	ErrMissingReservation    = errors.New("missing reservation")
 )
 
+func makeKeysAndArgs(req ...ReserveRequest) ([]string, []string) {
+	keys := make([]string, len(req))
+	args := make([]string, len(req))
+	for i, r := range req {
+		if r.Quantity <= 0 {
+			return nil, nil
+		}
+		keys[i] = getInventoryKey(r.SKU, r.LocationID)
+		args[i] = strconv.Itoa(int(r.Quantity))
+	}
+	return keys, args
+}
+
+func (s *RedisInventoryService) ReservationCheck(req ...ReserveRequest) error {
+	if len(req) == 0 {
+		return ErrMissingReservation
+	}
+
+	keys, args := makeKeysAndArgs(req...)
+	if keys == nil || args == nil {
+		return ErrInvalidQuantity
+	}
+
+	cmd := reserveScript.Run(s.ctx, s.client, keys, args)
+	if err := cmd.Err(); err != nil {
+		return err
+	}
+	if val, err := cmd.Int(); err != nil {
+		return err
+	} else if val != 1 {
+		return ErrInsufficientInventory
+	}
+	return nil
+}
+
 func (s *RedisInventoryService) ReserveInventory(req ...ReserveRequest) error {
 	if len(req) == 0 {
 		return ErrMissingReservation
 	}
 
-	keys := make([]string, len(req))
-	args := make([]string, len(req))
-	for i, r := range req {
-		if r.Quantity <= 0 {
-			return ErrInvalidQuantity
-		}
-		keys[i] = getInventoryKey(r.SKU, r.LocationID)
-		args[i] = strconv.Itoa(int(r.Quantity))
+	keys, args := makeKeysAndArgs(req...)
+	if keys == nil || args == nil {
+		return ErrInvalidQuantity
 	}
 	cmd := reserveScript.Run(s.ctx, s.client, keys, args)
 	if err := cmd.Err(); err != nil {
@@ -114,6 +144,47 @@ func (s *RedisInventoryService) ReserveInventory(req ...ReserveRequest) error {
 	return nil
 }
 
+var reservationCheck = redis.NewScript(`
+-- Get the number of keys passed
+local num_keys = #KEYS
+
+-- Ensure the number of keys matches the number of quantities
+if num_keys ~= #ARGV then
+  return {err = "Script requires the same number of keys and quantities."}
+end
+
+local new_values = {}
+local payload = {}
+
+-- ---
+-- 1. CHECK PHASE
+-- ---
+-- Loop through all keys to check their values first
+for i = 1, num_keys do
+  local key = KEYS[i]
+  local quantity_to_check = tonumber(ARGV[i])
+
+  -- Fail if the quantity is not a valid number
+  if not quantity_to_check then
+    return {err = "Invalid quantity provided for key: " .. key}
+  end
+
+  -- Get the current value stored at the key
+  local current_val = tonumber(redis.call('GET', key))
+
+  -- Check the condition
+  -- Fail if:
+  -- 1. The key doesn't exist (current_val is nil)
+  -- 2. The value is not > the required quantity
+  if not current_val or current_val <= quantity_to_check then
+    -- Return 0 to indicate the operation failed and no changes were made
+    return 0
+  end
+end
+
+return 1
+`)
+
 var reserveScript = redis.NewScript(`
 -- Get the number of keys passed
 local num_keys = #KEYS